A Long Island nurse says patients may have died at his hands — because his bosses at Nassau University Medical Center didn’t properly supervise or “support” him, according to a bombshell lawsuit.

Robert Reilly claims he was a novice RN when he took his first job at the East Meadow hospital — but was immediately assigned to the sickest patients in intensive care, while simultaneously enduring discrimination as the only white, male nurse on staff.

“It is believed that [harm to] the health and welfare, including possible wrongful death, of several patients may have resulted from [NUMC’s] negligence in failing to properly supervise, guide and support Reilly,” his Brooklyn federal court lawsuit claims.

Reilly, 42, says his first cases upon arrival in March 2010 were “the most complex and unstable patients” in the ICU, but not only did his more experienced colleagues fail to mentor him — they avoided him.

Unable to leave the unit unless a co-worker relieved him, Reilly says, he was often forced to work 18- or 19-hour shifts when no one would show up to take his spot.

Critically ill patients “should have been assigned to a more experienced RN,” Reilly says in court papers, but were “ultimately placed . . . in an unnecessarily precarious situation.”

The shocking claims could expose the 530-bed hospital to more legal problems, a medical malpractice expert says.

“Under certain circumstances, New York law requires that medical caregivers be supervised,” said attorney Sam Rosmarin.

But families of those who may have died because of shoddy care would have at least one legal hurdle to climb: a three-year statute of limitations, Rosmarin said.

Reilly’s female co-workers made it clear they didn’t want him on staff, Reilly claims.

Despite the long hours he worked without nurses to relieve him, he claims supervisors refused to approve his overtime pay, according to the East Islip man’s $200,000 legal claim.

His 11-month tenure at the hospital finally ended in January 2011 when NUMC allegedly threatened to report him to state authorities for what Reilly claims were “minor errors,” including once labeling a medicine incorrectly and failing to enter data in a timely manner. He resigned instead.

A lawyer for Nassau University Medical Center did not respond to a request for comment.